1. Field of the Invention
The present invention relates to a semiconductor device including a switching semiconductor element and a controlling IC for controlling the switching semiconductor element, and more specifically concerns a power module.
2. Description of the Related Art
Conventionally, an intelligent power module (IPM) containing a power circuit constituted by a switching semiconductor element and a control circuit for controlling the power circuit has a construction in which the power circuit and the control circuit constituted by an integrated circuit (IC) serving as a controlling IC are formed in a separated manner as two stages (FIG. 7), or the control circuit and the power circuit are integrally formed on one substrate (FIGS. 6 and 8).
Moreover, a power module shown in FIG. 6 has a construction in which an MOSFET (metal oxide semiconductor field effect transistor) 100 is connected to an electrode layer 6 on a heat sink 2 and a controlling IC 12 is bonded thereto by a bonding agent layer 16 through an insulating layer 14 on the MOSFET 100.
Here, a power module shown in FIG. 8 has a construction in which a switching semiconductor element 8, a FWDi 10, a printed substrate 110 and a case 102 are formed on an insulating substrate 4 on a heat sink 2. A controlling IC 12 is assembled on the printed substrate 110. The FWDi 10 is connected to the switching semiconductor element 8 and the printed substrate 110 by bonding wires 20. The switching semiconductor element 8 and the printed substrate 110 are connected to terminals, not shown, on the case 102, by respective bonding wires 20.
A power module, shown in FIG. 7, has an arrangement in which a switching semiconductor element 8 and a case 102 are placed on an insulating substrate 4 bonded to a heat sink 2, and a control substrate 104, supported by a relay terminal 106 on the case 102, is installed. Here, the switching semiconductor element 8 is connected to a relay terminal 106 by a bonding wire 20. The control substrate 104 contains a controlling IC for controlling the switching semiconductor element 8, etc. The relay terminal 106 is used so as to transmit driving input signals, driving output signals, detection signals for current, voltage and temperature, etc. of the switching semiconductor element between the switching semiconductor element 8 and the controlling IC on the control substrate 104.
Moreover, with respect to a semiconductor device having a construction in which a control circuit constituted by semiconductor elements, and a power circuit, etc. are integrally formed, Japanese Laid-Open Patent Publications No. 6-181286, No. 63-87758, No. 3-226291, No. 11-163256 and No. 8-167838 have disclosed such a construction.
Japanese Laid-Open Patent Publication No. 6-181286 discloses a semiconductor device having a construction in which a controlling IC chip is bump-connected onto a power IC chip fixed to a heat sink through a thin-film substrate.
Japanese Laid-Open Patent Publication No. 63-87758 discloses a semiconductor device having a construction in which a controlling IC is joined to a power MOSFET fixed to a heat sink.
Japanese Laid-Open Patent Publication No. 3-226291 discloses a semiconductor device having a construction in which an IGBT (insulated gate bipolar transistor), an FWDi (Free Wheeling Diode) and a controlling IC are formed into one chip.
Japanese Laid-Open Patent Publication No. 11-163256 discloses a semiconductor device having a construction in which on a semiconductor chip on a heat radiation plate is superposed another semiconductor chip, that is, a so-called chip-on-chip construction, and Japanese Laid-Open Patent Publication No. 8-167838 discloses a semiconductor device having a construction in which a plurality of power-MOSFETs and a control circuit are integrated as one chip.
For example, in a structure of a semiconductor device shown in FIG. 6, in the case when a controlling IC 12 is attached to an MOSFET 100 (IGBT or power MOSFET) by means of a bump, an insulating layer 14, a bonding-agent layer 16 or a press-joining, etc., a problem arises in which the controlling IC malfunctions due to heat generated by the switching semiconductor element 8. Here, MOSFET 100 serves as the switching semiconductor element constituted by a power circuit. Moreover, in the case when the controlling IC 12 is packaged inside the switching semiconductor element 8 also, the same problem arises in which the controlling IC malfunctions due to heat generated by the switching semiconductor element 8. Therefore, the problem with the semiconductor devices having the constructions disclosed in Japanese Laid-Open Patent Publications No. 6-181286 and No. 63-87758 is that the controlling IC is susceptible to malfunctions due to heat.
Moreover, in the semiconductor device disclosed by Japanese Laid-Open Patent Publication No. 3-226291 also, a problem arises in which the controlling IC malfunctions due to heat generated by the IGBT, depending on the positional relationship between the IGBT and the controlling IC.
Furthermore, as illustrated in FIG. 7, in the case when, in a power module, the MOSFET or the IGBT serving as a switching semiconductor elements 8, the FWDi 10 (Free Wheeling Diode) and the controlling IC 12, etc. are constructed in a separated manner, the number of parts related to the construction increases and the construction becomes complex, resulting in high costs in the module per unit. Another problem is that the power module as a whole becomes comparatively large.
In the case of the power module shown in FIG. 8 also, a problem arises in which the power module as a whole becomes comparatively large.
The present invention has been devised to solve the above-mentioned problems, and its objective is to make the power module as a whole compact, and to provide an inexpensive power module which can prevent malfunction of the controlling IC due to heat generated by the switching semiconductor element, while maintaining resistance to switching noise from the switching semiconductor element.
The power module of the first aspect of the present invention, which has been devised to solve the above-mentioned problems, is provided with an insulating substrate having a base plate bonded to one of faces thereof and a circuit pattern formed on the other face as an electrode layer, the circuit pattern including: a switching semiconductor element, a free wheeling diode connected to the switching semiconductor element in anti-parallel therewith, and a controlling IC for controlling the switching semiconductor element, and in this arrangement, the controlling IC is formed on the free wheeling diode.
In accordance with the power module of the first aspect of the invention, since the controlling IC is placed on the FWDi which generates less heat upon operation than the switching semiconductor element it is possible to prevent the controlling IC from malfunctioning due to heat generated by the switching element. Therefore, it becomes possible to improve reliability of the power module.
The power module of the second aspect of the present invention, which relates to the power module of the first aspect, is characterized in that the switching semiconductor element and the free wheeling diode are constructed as a monolithic integrated circuit.
In accordance with the power module of the second aspect of the present invention, the switching semiconductor element and the free wheeling diode are constituted as a monolithic integrated circuit; therefore, it is possible to make the power module compact, and also to simplify the construction thereof. Thus, it becomes possible to increase the productivity in the wafer manufacturing process and the assembling process of the semiconductor, and consequently to reduce the unit price of the power module.
The power module of the third aspect of the present invention is provided with an insulating substrate having a base plate bonded to one of faces thereof and a circuit pattern formed on the other face as an electrode layer, the circuit pattern including: a switching semiconductor element, a free wheeling diode connected to the switching semiconductor element in anti-parallel therewith, and a controlling IC for controlling the switching semiconductor element, the switching semiconductor element, and in this arrangement, the free wheeling diode, the switching semiconductor element and the controlling IC are constructed as a monolithic integrated circuit with at least one portion of the free wheeling diode being sandwiched between the switching semiconductor element and the controlling IC.
In accordance with the power module of the third aspect of the present invention, the switching semiconductor element, the free wheeling diode and the controlling IC are constituted as a monolithic integrated circuit; therefore, it is possible to make the entire power module compact, and also to simplify the construction thereof. Thus, it becomes possible to increase the productivity in the wafer manufacturing process and the assembling process of the semiconductor, and consequently to reduce the unit price of the power module. Moreover, this type of power module makes it possible effectively prevent heat generated by the switching semiconductor element from thermally conducting to the controlling IC, and consequently to prevent the controlling IC from malfunction. Therefore, it becomes possible to improve the reliability of the power module.
The power module of the fourth aspect of the present invention is provided with an insulating substrate having a base plate bonded to one of faces thereof and a circuit pattern formed on the other face as an electrode layer, the circuit pattern including: a switching semiconductor element, a free wheeling diode connected to the switching semiconductor element in anti-parallel therewith, and a controlling IC for controlling the switching semiconductor element, the switching semiconductor element, and in this arrangement, the switching semiconductor element and the free wheeling diode are constructed in a separated manner, and the free wheeling diode and the controlling IC are constructed as a monolithic integrated circuit.
In accordance with the power module of the fourth aspect of the present invention, the free wheeling diode and the controlling IC are constituted as a monolithic integrated circuit; therefore, it is possible to make the entire power module compact, and also to simplify the construction thereof. Thus, it becomes possible to increase the productivity in the wafer manufacturing process and the assembling process of the semiconductor, and consequently to reduce the unit price of the power module. Moreover, this type of power module makes it possible effectively prevent heat generated by the switching semiconductor element from thermally conducting to the controlling IC, and consequently to prevent the controlling IC from malfunction. Therefore, it becomes possible to improve the reliability of the power module.
The power module of the fifth aspect of the present invention, which relates to any one of the first aspect to the fourth aspect is characterized in that the switching semiconductor element is an insulating gate type element (for example, an IGBT, a power MOSFET, etc.).
In accordance with the power module of the fifth aspect of the present invention, an insulating gate type element (for example, an IGBT, a power MOSFET, etc.) is used as the switching semiconductor element. This makes it possible to use the power module at comparatively great operational frequencies.